1. Field of the Invention
This invention relates to kerfed structural sheeting units such as kerfed ceiling tile.
2. Description of the Prior Art
Easily breakable structural sheeting units, such ceiling tiles, can have the edges thereof easily damaged during transport and handling. In the industry, this results in a rather large amount of rejections due to damage. One way of overcoming this problem is to have inverted-T runners for supporting the tile with the runner covering the damaged portion. However, in many instances it is desirable to have a concealed ceiling panel i.e. a panel in which the inverted-T runners do not show. When this type of design is desired, the breakage or damage to the edges becomes significant in that it requires rejection of the entire panel. Prior attempts to overcome this problem have resulted in some type of offsetting of the kerfed edges to protect the visable edge, but such a construction has always limited the use of the ceiling tile and required construction in only one or two limited directions in order to accommodate the design features required to protect the visible edge.
Building panels having breakaway edges are not new. In U.S. Pat. No. 3,488,248, a roofing panel has a portion of the edge capable of being broken away from the remainder thereof in order that the remaining portion of the edge, consisting of an overlay of the actual product, can be overlapped on the corresponding edge of an adjacent panel to provide a decorative surface. The breakaway portion of this panel, however, does not extend past the covering portion and, therefore, will not protect it from a blow being directed against the edge thereof. In British Patent Specification No. 1,079,139 building panels are provided with breakaway portions made from a V-shaped groove, but, again, the extended portion will not serve as a protection against the portion that is remaining after the breakaway section is removed. In British Pat. No. 1,403,193, building units having breakaway sections are provided, but an entire section is broken away and the remaining portion cannot properly be called a kerfed section nor is it protected by the broken away portion since the remaining portion is not recessed. Additionally, these panels require disposal of major parts of the building material when the broken away portion is removed. Likewise, in Italian Pat. No. 534,078, breakaway portions are provided in building panels, but the portion to be broken away does not protect the remaining portion from damage due to a blow on the edge, and the portion is to be broken away merely as a design feature for engaging another similarly situated or corresponding panel. A similar situation exists in Swiss Patent No. 459,516 wherein the removable portion is so far removed from the remaining portion that it affords no protection from edge damage due to a blow being directed at the edge of the panel.
In U.S. Pat. No. 3,686,060, an extention of one, and only one, edge of the panel is provided but it is so weak (made of only wrapping paper) that it affords absolutely no protection against a blow being directed against the edge portion of the wrapping material. In U.S. Pat. No. 3,516,212, edges of a panel are adapted to be broken away, but the portions thereof are not constructed in such a manner as to afford edge protection against a blow being directed against the edge of the panel. Furthermore, the breakable portion is an extension of the decorative surface thereof, thereby constituting removal of an expensive portion of the building product. In U.S. Pat. No. 2,951,318, grooves are used in a building block to enable a portion thereof to be broken away from the block, but the projections provide no protection for the other side of the edge when a blow is directed against the edge of the building block. In U.S. Pat. No. 2,781,657 a similar type design is used, but the breakaway portion provides no protection for the opposing edge when a blow was directed against the edge of the panel of construction. In U.S. Pat. No. 1,809,393, breakaway portions enable the remaining pieces to act as an inlay and fit into kerfed floor material. In this patent, however, the remaining portion is not sought to be protected against visual damage but it is only required that it maintain some sort of structural integrity which will enable it to be forced into the hardwood flooring material. Finally, in U.S. Pat. No. 1,289,492, slots are provided in roofing tile to enable a portion of a tile to be broken away from the remaining portion, but this does not serve the purpose of having the remaining portion extend outward and be protected by the portion to be broken away, and, actually it merely serves as an expedient for construction rather than as a protection against edge damage.
Prior attempts for protecting edges of building panel structures have either been expensive due to removal of large amounts of the building material or else have been inadequate in providing for protection against edge damage. The new and novel design of this invention provides for edge protection of easily damagable building units at a cost which is less than the cost of units normally being rejected due to such damage.